The transmission of an automobile is a speed-changing device. The transmission is installed in the drive train that connects the crankshaft of the engine to the driving wheels. This permits the engine to operate at a higher speed when its full power is needed and to slow down to a more economical speed when less power is needed. Under some conditions, as in starting a stationary vehicle or in ascending steep grades, the torque of the engine is insufficient, and amplification is desired. Most devices employed to change the ratio of the speed of the engine to the speed of the driving wheels multiply the engine torque by the same factor by which the engine speed is increased.
The only major difficulty in the operation of the early manual sliding-gear transmission was the need for simultaneously operating the accelerator pedal, the clutch pedal, and the gearshift lever. The automatic transmission was developed to eliminate this manipulation. Most automatic transmissions employ either a fluid coupling or a hydraulic torque converter, a device for transmitting and amplifying the torque produced by the engine. Each type provides for manual selection of reverse and a low range that either prevents automatic upshifts or employs a lower gear ratio than is used in normal driving. By 1970 the hydraulic torque converter-type automatic transmission dominated its field. In hydraulic transmissions, shifting is done by a speed-sensitive governing device that changes the position of valves that control the flow of hydraulic fluid. The vehicle speeds at which shifts occur depend upon the position of the accelerator pedal, and the driver can delay upshifts until higher speed is attained by depressing the accelerator pedal further. Control is by hydraulically engaged bands and multiple disk clutches running in oil, either by the driver's operation of the selector lever or by a speed-sensitive governor. Compound planetary gear trains with multiple sun gears and planet pinions have been designed to provide a low forward speed, an intermediate speed, a reverse, and a means of locking into direct drive. This unit is used with various modifications in almost all hydraulic torque-converter transmissions.
In hydraulic torque-converter transmissions, torque is multiplied by means of gear trains and a hydraulic member with three or more elements. Oil in the housing is accelerated outward by rotating vanes in the pump impeller and, reacting against vanes in the turbine impeller, forces them to rotate. Oil then passes into the stator vanes, which redirect it to the pump. The stator serves as a reaction member providing more torque to turn the turbine than was originally applied to the pump impeller by the engine. Blades in all three elements are specially contoured for their specific function and to achieve particular multiplication characteristics. Through a clutch linkage, the stator is allowed gradually to accelerate until it reaches the speed of the pump impeller. The hydraulic elements are combined with two or three planetary gear sets, which further provide torque multiplication between the turbine and the output shafts.
In the maintenance and repair of automatic transmissions, it is usually necessary to remove the transmission from the vehicle and dismantle it in order to adequately inspect all of the components thereof. Automatic transmissions are generally heavy, bulky objects which are not easy to handle or move. Furthermore, it is preferable that certain areas of the transmission are not forced to carry substantial weight due to their fragile nature. Therefore, it is desirable to have a stable support which can allow the transmission to be easily and quickly maneuvered without causing harm to the body of the transmission.
Importantly, during the repair of transmissions, the torque converter generally lies loosely within the interior of the- bell housing of the automatic transmission. During typical transmission repair operations, the torque converter will fall from the bell housing or will constantly be tossed to-and-fro. In the storage of automatic transmissions, the torque converter often becomes lost, misplaced, or otherwise separated from the transmission housing from which it originated. Even when the torque converter is retained within the bell housing of the transmission, the shafts associated with the torque converter can become damaged, distorted, or otherwise inappropriate for continued use. Therefore, it is very desirable to maintain the stability of the torque converter within the bell housing of the transmission during transport, storage, and repair of transmissions.
One U.S. patent, in the past, has addressed the need for tools and fixtures during the movement of transmissions. U.S. Pat. No. 4,307,877, issued on December 29, 1981, to D. D. Rogos describes a rigid elongated framework which contains a transverse mounting member at one end for attachment to the bell housing of the transmission. A belt is wrapped around the opposite end of the framework and transmission to pull the transmission forward into the framework. A central extendible support member is moved into engagement with the center of the transmission body to insure secure engagement between the transmission and the framework. The framework and transmission can be moved between several positions for providing easy access to any part of the transmission. This device, however, did not provide a suitable mechanism for the retention of the torque converter within the bell housing of the transmission.
It is a object of the present invention to provide a carrying device for a bell housing of a transmission which is suitable for allowing workers to lift the transmission. It is another object of the present invention to provide a carrying device that includes a suitable mechanism for the retention of a torque converter in its natural position within the bell housing.
It is another object of the present invention to provide a carrying device and a torque converter retention device which is easy to manufacture, easy to use, and relatively inexpensive.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.